Cooling apparatus



a M m 0 3 mm W n w. mm? V UP L l l M Y Wm" H H B No mm 2 F F. P. TAUGHERCOOLING APPARATUS Filed May 29, 1955 Mairch 18, 1941.

Watcnicd Mar. '18, 1941 NITED STATES COOLING APPARATUS Frank P. Tougher,Clayton, Ma, assignor to Westinghouse Electric 8; Manufacturing Company,East Pittsburgh, Pat, a corporation of Pennsylvania Application May 29,1935, Serial No. 24,00l

' 3 Claims.

My invention relates to refrigerating apparatus, more particularly tosuch apparatus including a plurality of evaporator passages arranged iniii parallel with respect to refrigerant flow, and it has for an objectto provide improved apparatus.

Another object is to supply liquid refrigerant to said evaporatorpassages in substantially equal proportions, or in any other desiredproportions.

In a mechanical system of refrigeration, as the pressure of thecondensed refrigerant is reduced hei'ore admitting the same to theevaporator, a portion of the refrigerant is vaporized, producing amixture of liquid and vaporous refrigerant. For certain purposes, suchas for comfort cooling of air, it is desirable to use an evaporatorcomprising a plurality of coils or evaporator passages, which aredesigned to do equal amounts of cooling. When the inlet ends of theevaporator coils are connected to the bottom of a header into which themixture of liquid and vaporous refrigerant is admitted for distributionto the coils, it has been found that some of the coils receive mostlyliquid refrigerant while others will receive mostly vaporousrefrigerant. Due to the fact that the vaporous refrigerant has done mostof its work in cooling the liquid refrigerant by the absorption of heatof vaporization, it has relatively little cooling capacity, and thecoils receiving mostly vaporous refrigerant will be relatively warm andineffective to do cooling.

In accordance with my invention, I provide a refrigerant supplyheader,and a plurality of evaporator passages. whose inlet end portions projectvertically into the header and terminate in a common plane between theupper and lower ex ti'elnities oi the interior of the header.Preferably, said inlet end portions project upwardly throueh the bottomof the header but they may project downwardly through the top of thehead er. ll ioody of liquid refrigerant is thus accumu lated in theheader from which the evaporator passages receive liquid in equalproportions when the evaporator passages are identical, or in precistermined portions when they are not alike.

\Tihe above and other objects are effected by my invention as will beapparent from the fol lowing description and claims taken in connec tionwith the accompanying drawing, forminga part of this application, inwhich:

his. 1 is a diagrammatic view of refrigerating apparatus embodying mynovel evaporator, the latter being shown in side elevation;

li ies. 2 and 3 are end views of the left and right hand ends of theevaporator as seen in Fig,

1 l; and

(El. lid-126) Figs. 4 and 5 are detail views of two modifications of adetail.

Referring to the drawing in detail, I show an evaporator ill disposed inan air duct H. with the coils extending across the duct. A fan i),driven by a motor l3, circulates the air through the duct and over thecooling surfaces of the evaporator. The evaporator comprises a pluralityof coils it, live such coils being shown. Each coil comprlses-tubesorconvolutions 15 to 23, inclusive, through which the refrigerant flowssuccessively, the adjacent ends of the successive tubes being connectedby connecting portions it. As shown on the drawingthe tubes IE to Illare arranged in one horizontal row so that the air flows over the tubesin the order named, and the tubes 20 to 23 are arranged in a rowimmediately below the first row and so that air flows over the coilsinversely oi the order in which refrigerant flows therethrough. Theseveral coils are arranged in superposed relation, so that they are inparallel with respect to air flow. This arrangement of the coils in theevaporator is disposed and claimed in the application of E. R. Wolfert,Serial No. 702,387. Plates or fins 23 are preferably applied to thetubes, extending transversely thereof, for the purpose of providingextended heat transfer surfaces, as is old and well understood in theart. r

The tubes comprising the coils are mounted in end walls ill and it,connected by top and bottom walls 2% and 21, said four walls forming achassis or frame structure for the evaporator. The front and back sidesare open to provide for flow of air over the coils.

A refrigerant supply header or manifold 26 is provided, being disposedin the illustrated embodiment adjacent the upper edge of thewall 25. Theseveral coils are provided with inlet end portions 29, connected to theinlet ends of the tubes id 01 the several coils. Said inlet end portions29 project upwardly through the bottom of the heador 28 into theinterior thereof, and terminate intermediate the upper and lowerextremities of the interior of the header, as shown in Figs. i and 3.The upwardly opening inlet ends are disposed at substantially the samelevel, that is, substantially in a common horizontal plane. The outletends of the several coils, that is, the outlet ends of the tubes iii,are connected to a suction header 3|] through tube portions it. In thepresent em" hodiment, the coils Ii are identical in dimensions andconstruction, and the inlet end portions 29 are oi identical circularcross-section, though of varying length. I

The refrigerating unit for supplying the evaporator with refrigerantincludes a compressor 3| driven by a motor 32. The inlet of thecompressor is connected through a conduit 33' with the suctionheader 30,and the outlet thereof is connected through a conduit 34 to a condenser35. The latter discharges into a liquid receiver 36 from which liquidrefrigerant is conveyed through a conduit 31 to an expansion valve 18.The expansion valve 38 may be any suitable pressure reducing deviceknown in the art, but I prefer to use a device of the type known as athermostatic expansion valve which includes a thermostatic bulb isconnected thereto through a tube 4| and responsive to the temperature ofthe vaporized refrigerant returned to the compressor. Such a devicecontrols the flow of refrigerant so as to maintain a pressure on thedischarge side of the valve which is in predetermined relation to thetemperature of the vaporized refrigerant; in other words, to maintain aconstant degree of superheat of the vaporized refrigerant returned tothe compressor.

The refrigerant discharged at low pressure from the expansion valve isconveyed through a conduit 42 to the refrigerant supply header 2. of theevaporator Ill. The conduit 42 may be connected with the header 28 atany suitable point, but preferably it is connected to the bottom thereofintermediate two of the inlet, portions 2!, as shown in Fig. 3.

The operation of the above-described apparatus is as follows:

vaporized refrigerant discharged from the coils is conveyed through theconduit 33 to the compressor wherein it is compressed. It then flowsthrough the conduit 34 to the condenser 15 in which it is reduced toliquid state and delivered to the liquid receiver 3'. From the latter,it flows through the conduit 31 to the expansion valve 38, which iscontrolled as mentioned above. As the refrigerant passes through theexpansion valve, its pressure is reduced, causing a portion of therefrigerant to be vaporized in reducing the temperature thereof to thesaturation temperature corresponding to the reduced pressure. The

mixture of liquid and vaporous refrigerant flows through the conduit 42to the refrigerant supply header 28.

The vaporous refrigerant enters the header in a turbulent state. Part ofthe vapor segregates from the liquid and goes to the top immediately. Aportion of the gas remains suspended in the liquid and bubbles out asthe liquid seeks the bottom level. In the present case the liquid andsuspended gas collect in a body 43 having a deflnite level, indicated.on the drawing 44, while the vapor as it collects and bubbles oif fillsthe pocket 45 above said level. This level M is just above the inletends of the evaporator coils or passages. which are at the same level.so that the liquid flows over the end edges thereof into the coils,while the vapor enters the central portions of the inlet ends of thecoils. Inasmuch as the several coils have equal perimeters at the inletends, the quantities of liquid received will be equal, as will also thequantities of vapor. When the inlet ends are not equal, they willreceive liquid refrigerant substantially in proportion to the perimetersof their inlet ends. The header 28 should be sufficiently large,relative to the coils It, to obtain a velocity of refrigerant fluid inthe header which is suflicientlyi low to permit the liquid to acquire asubstantially placid liquid surface. For example, in an evaporator for a2 or 4 ton refrigerating system, the header 2! may have an insidediameter of 1.25 inches.

The liquid level 44 is maintained substantially constant, Just above theinlet ends, since any tendency to drop will result in an accumulation ofliquid which brings the liquid level up, while a tendency to riseresults in an accumulation of vapor which forces the level down.

While I have shown the inlet ends cut off on a horizontal plane, atright angles to the axes of said inlet ends, it is to be understood thatthe invention is not so limited. The inlet ends may be of any suitableform, as described below, but they should be identical where equalquantities of liquid refrigerant are desired.

The liquid and vaporous refrigerant then flow through the convolutionsor tubes It to 23 of the coils, successively. As the liquid passesthrough the several tubes, it absorbs heat from the air circulated bythe fan [2 and is vaporized, and the vaporous refrigerant also absorbssome degree of sensible heat. When the evaporator is used forcomfortcooling of air, the temperature of the refrigerant varies between about30 F. and 50 F. The vaporized refrigerant is discharged from the severalcoils through the tube portions ll into the suction header ii to bereturned to the compressor for recirculation.

In the modification shown in Fig. 4, each inlet end portion 29a isslotted adjacent the inlet end, as shown at 48. The liquid refrigerantenters the coil entirely or mainly through the slots. With this form,the distribution of liquid refrigerant to the several coils is lessaifected in case the header is not disposed exactly level or the inletends are not at exactly the same level. The liquid level rises to theupper ends of the inlet end portions 28a or adjacent thereto so that, ifone inlet end portion is somewhat higher than others, it still has mostof its slot below the surface of the liquid and receives substantiallyits portion of liquid.

In Fig. 5, the upper edges of the inlet end portions flbare serrated,which form also tends to equalize the flow of liquid into the coils.

While I have, shown my invention in three forms, it will be obvious tothose skilled in the art that it is not so limited, but is susceptibleof various other changes and modifications, without departing from thespirit thereof, and I desire, therefore, that only such limitationsshall be placed thereupon as are imposed by the prior art or as arespecifically set forth in the appended claims.

What I claim is:

1. In refrigerating apparatus, the combination of an evaporator, acompressor for withdrawing vaporized refrigerant from the evaporator andcompressing the same, means for condensing the compressed refrigerant,expansion valve means for reducing the pressure of the condensedrefrigerant and discharging the same in the form of a mixture of liquidand vapor, said evaporator comprising a refrigerant supply headerreceiving said mixture and a plurality of evaporator passages, the inletends of said evaporator passages opening upwardly into 'said header'at'substantially the same level intermediate the upper and lowerextremities of the interior thereof, whereby said passages receiveliquid refrigerant substantially in desired predetermined proportions.

.2. In refrigerating apparatus, the combination of an evaporator, acompressor for withdrawing vaporized refrigerant from the evaporator andcompressing the same, means for condensing the an mi eompressedrefrigerant, expansion valve means ior reducing the pressure of thecondensed re irigerant and discharging the same in the form oil amixture of liquid and vapor, said evaporator comprising a refrigerantsupply header and a plurality of evaporator passages, means forconveyi'ng said mixture of liquid and vaporous reirigerant through saidsupply header and through said evaporator passages, said evaporatorpassages having inlet end portions, each of equal perimeter, openingupwardly into said supply header at substantially the same levelintermediate the upper and lower extremities of the interior thereof,whereby said evaporator passages receive vapor and liquid refrigerantsubstantially in equal proportions.

' 3. In refrigerating apparatus, the combination of a plurality ofevaporator passages, a refrigerant supply header therefor, means fordelivering a mixture of vapor and liquid refrigerant to said header andmeans to distribute the mixture of vapor and liquid refrigerant to theevaporator passages in equal proportions, said last-mentioned meanscomprising the inlet end portions of said evaporator passages, whichportions project upwardly into said supply header and terminate in equalperimeters at substantially the same level intermediate the upper andlower extremities of the interior thereof.

i. In refrigerating apparatus, the combination of a plurality ofevaporator 1.1 es, 9. refrigerant supply header therefor, means fordelivering a mixture of vapor and liquid refrigerant to said header andmeans to distribute the mixture of vapor and liquid refrigerant inpredetermined proportions to the evaporator es, said lastmentioned meanscomprising the inlet end portions of said evaporator es, which portionsproject upwardly into said supply header and terminate at substantiallythe same level intermedi ate the upper and lower extremities of theinterior evaporator elements comprising a header having an inlet for themixture of liquid and vaporous refrigerant and a plurality of conduitsextending upwardly into said header and having openings communicatingwith the interior of the header,

the openings being similarly formed and the ermost points thereof beingdisposed substantially above the bottom and below the top of theinterlor of the header and at the same level, said conduitscommunicating with the respective evaporator elements.

o. In refrigerating apparatus having a plurality oi evaporator elements,a device for distributinga mixture of liquid and vaporous refrigerant inpredetermined proportions to the evaporator elements comprising a headerhaving an inlet for the mixture of liquid and vaporous refrigerant and aplurality of conduits extending vertically into said header andcommunicate ing with the respective evaporator elements, said conduitshaving relatively narrow, vertically elongated openings communicatingwith the interior of said header, the lowermost points of said openingsbeing disposed substantially above the bottom and below the top of theinterior of said header and at the same level,

'I. In refrigerating apparatus having a plurality of evaporatorelements, a device for distributing a mixture of liquid and vaporous refrigerant in predetermined proportions to the evaporator elementscomprising a header having an inlet for the mixture of liquid andvaporous refrigerant and a plurality of conduits ex-' tending upwardlyinto said header and having.

openings communicating with the interior of the header. the lowermostpoints of said openings being disposed above the bottom and below thetop of the interior of the header and at the same level, said conduitscommunicating with the respective evaporator elements.

8. In refrigerating apparatus having a plurality of evaporator elements,a device for distributing a mixture of liquid and vaporous refrigerantin predetermined proportions to the evaporator elements comprising aheader having an inlet for the mixture of liquid and vaporousrefrigerant and a plurality of conduits extending upwardly into saidheader and having openings communicating with the interior of theheader, the lowermost points of said openings being; disposed at thesame level and said openings being of such size and dispositon as tomaintain a liquid level in said header below the top and above ments. a

FRANK P. TAUGHER.

